A wide variety of implements using coils of coil-wire snakes have been developed over the years in order to facilitate the cleaning of drain pipes and the like. A number of such implements have included a generally cylindrical cannister which contains the coiled snake, means to remove one end of the snake to whatever extent is necessary for insertion into the clogged pipe or the like, and some means for turning the cannister in order to turn the snake for drain-cleaning purposes. Some of such cannisters are plastic shells which are formed of two subshells secured together in various ways.
While spin welding or ultrasonic welding and other plastic-sealing techniques have been used for this purpose, in some cases the subshells have been snap-fit together using a plurality of pairs of male-female snap means along abutting annular edges of the two subshells. While this has certain advantages in ease of original assembly, such products do have certain problems and shortcomings.
For example, the plastic subshells having such mating means formed therein have been somewhat susceptible to breakage by virtue of the edges and corners which have been characteristic of such structural features in such products. When such drain-cleaning implements are dropped, breakage can frequently occur along such edge lines and corner lines.
Another problem relates to the need to achieve proper snap engagement of such subshells. This problem requires a somewhat lengthy explanation.
Such plastic subshells frequently do not come out of the mold in true round condition. That is, the annular edges of such subshells, which are to abut each other when such subshells form a complete shell, frequently are not true round prior to and at the time such subshells are assembled together. Therefore, the male and female mating means on such subshells often do not engage each other as fully as is desired. It is helpful that the coiled snake inside an assembled shell exert some outward force on the shell to bring it closer to true round, and thus assist in full mating of the subshells.
In certain structures of the prior art, the inside surface of one of the subshells has had inwardly-projecting sidewall portions (or built-up portions) formed at intervals around the inside surface of the cylindrical subshell wall in order to accommodate the male mating means used for snap engagement of the two subshells. More specifically, such inwardly projecting sidewall portions extend beyond the abutting edge of the subshell (on which they are formed) as projections with outwardly-facing male means thereon to engage female means on the other subshell. Such inwardly-projecting sidewall portions formed at intervals around the inside surface of the subshell have provided good pressure points for the coiled snake within the plastic shell, and have allowed application of relatively effective outward pressure by the coiled snake at positions near the male mating means. This has encouraged proper and full engagement of the pairs of mating means fairly well.
However it is such inwardly-projecting sidewall portions that have produced the aforementioned significant edges across the cylindrical walls of the subshell and provide lines of weakness increasing the likelihood of breakage upon dropping or other rough handling. Mere thickening of the subshell walls, while providing strengthening through elimination of edge lines, would remove the advantage of effective pressure points for application of outward force by the coiled snake to assist in full engagement of the mating means and in making the plastic shell round. Thus, the normal solution for one problem leads to another problem, the loss of a most effective engagement assist which could be provided by the coiled snake.
Another problem with such prior plastic shells used for drain-cleaning implements in the prior art relates to improper relative rotation of the handle which, on such products, is rotatably mounted on a stem or other mounting means extending from tne plastic shell. Such handles, which are normally gripped in one hand while the plastic shell and the snake are turned by the other, are often improperly mounted on the stem because of improper positioning of a clamp ring on such stem. Such clamp ring is used to hold the handle in place and also to clamp the snake to the stem when the proper length of such snake has been pulled from the plastic shell for use.
Such improper positioning can cause the handle to bind on the stem, so that the two parts do not rotate properly with respect to each other, or can cause the handle to be too wobbly.
There is a need for significant improvement in the plastic shell to overcome the aforementioned disadvantage and problems.